Honestly, in my opinion it kind of is (though I’m not an expert on it). Except for convenience I don’t think a browser should be allowed to access my USB devices. Though I would welcome it if it was enabled with the same kind of request that pops up when a browser wants to access the microphone or camera.
Unfortunately not all features are always available on those ROMs.
One example is GrapheneOS and Google Wallet which I cannot use due to GrapheneOS not being considered “certified software” by the app and therefore not being trusted.